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barkerm

Alright, apologizing in advance. VDI + 1/4” both at the same time. . . BAD?

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I’m sure this has already been covered, so apologies in advance. But there is SOOOOO much info in the support section, who can find anything specific? I already searched ad nauseum!

 

Anyway, I’ve seen stuff that says “Don’t Do THAT!” regarding plugging a Variax (mine is a JTV89F from a few years ago) into your Helix with BOTH the 1/4” AND the VDI thing. Does that still apply? And what if I want to use “Boston’sPizza” . . . Both cables? Will that blow up my guitar (I've already done that once!)? If this is part of the “nauseum?” I’m so sorry, just a bit timid about frying a $1.4k guitar AGAIN! Anyone?

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Yes. Bad. The powers that be have harped on it since day one... it contributes to global warming and will get your grandmother hooked on meth. 

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Well you have to do it to do a firmware update using the dongle, but there is no power on the VDI for that. The issue is borderline overloading of some components due to too much current being drawn.

 

The real question is why do you want to do it?

 

If you have VDI going to a Helix or HD500 then both of those can split Models or Magnetics onto separate outputs using an FX loop which gives the same result without the weight of two cables on the socket assembly.

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55 minutes ago, Rewolf48 said:

Well you have to do it to do a firmware update using the dongle, but there is no power on the VDI for that. The issue is borderline overloading of some components due to too much current being drawn.

 

The real question is why do you want to do it?

 

If you have VDI going to a Helix or HD500 then both of those can split Models or Magnetics onto separate outputs using an FX loop which gives the same result without the weight of two cables on the socket assembly.

 

You're supposed to use the battery to do the updates. It could still mess things up.

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14 hours ago, cruisinon2 said:

Yes. Bad. The powers that be have harped on it since day one... it contributes to global warming and will get your grandmother hooked on meth. 

 

 

Well my grandmother’s already hooked on meth and I don’t believe in global warming. Good to go!!

  • Haha 1

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Don't do that. Have had guitars come back with circuits that failed because of running it using both outputs.

Trying to keep all your gear off of my repair bench. Please don't do that.

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Thanks all for the great info (and grandma stories!!). I see that the pickups can route through the VDI as mentioned above, so no need to connect both. Pretty much takes care of it. I don't think there is any mention of the problem in the manual though . . . maybe I just missed it.

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If you want to use the 1/4 output, and don’t want to relay on batteries, you can use any of the old Variax external power supplies with any JTV guitar. That will provide power through the TRS cable.

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Right,... the XPS works fine. Just don't run simultaneously with the VDI,... the Variax

circuits are not designed for that kind of current draw.

 

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Ok, now I'm a bit confused (AGAIN)! I don't use the cabled power kit (EVER - cuz I don't have one). I either plug in 1/4" (TS, NO "R", and NOW fearing to do that AND VDI simultaneously could blow up my JTV-89F . . . do I just not get it?) OR VDI. Sometimes 1/4" (TS) AND VDI. Is it the dueling power sources that are the problem????!!!! (drama emphasis added . . . just for fun!)

 

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22 hours ago, barkerm said:

Ok, now I'm a bit confused (AGAIN)! I don't use the cabled power kit (EVER - cuz I don't have one). I either plug in 1/4" (TS, NO "R", and NOW fearing to do that AND VDI simultaneously could blow up my JTV-89F . . . do I just not get it?) OR VDI. Sometimes 1/4" (TS) AND VDI. Is it the dueling power sources that are the problem????!!!! (drama emphasis added . . . just for fun!)

 

 

The answer is 2 posts above this one. Just don't run both outputs simultaneously. There's no earthly reason to do so anyway. Pick your favorite...end of story. 

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17 hours ago, barkerm said:

Ok, now I'm a bit confused (AGAIN)! I don't use the cabled power kit (EVER - cuz I don't have one). I either plug in 1/4" (TS, NO "R", and NOW fearing to do that AND VDI simultaneously could blow up my JTV-89F . . . do I just not get it?) OR VDI. Sometimes 1/4" (TS) AND VDI. Is it the dueling power sources that are the problem????!!!! (drama emphasis added . . . just for fun!)

 

 

To answer your power question, the problem has to do with how the circuit distributes current and with both a regular (TS no R) guitar cable and VDI it distributes the current in a way that will more than likely blow it up. I say more than likely because you can get lucky and it won't blow it up. But if you keep doing it, it will. Why is the circuit designed that way? Don't know. And using the cabled power kit with the VDI would, I assume, have even more dire effects. So no matter what you're doing, VDI only or 1/4" whatever only. NEVER both at the same time. Same time BAD!!!!!

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Whether models or mags,....

TS and VDI,...

TRS and VDI,... don't do that.

1/4" TRS OR VDI,.... not both together,...  one OR the other, at any given time.

 

Thank you.

 

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Great. Got it (I hope).  :D

 

Thanks again all!

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Just to be clear, the controversy here is that some people think the 1/4" TS output with the magnetic pickups sounds better/warmer than the magnetic pickups through the VDI cable. That might make sense since the magnetic pickups are converted to digital in the Variax and sent over the VDI cable. And it's not clear what impedance load is being applied to those magnet pickups before conversion to digital in the JTV - but I suspect its fixed at High-Z. If you use a 1/4" output into Helix Guitar input, the A2D conversion is being done in Helix, not the Variax, and Helix controls the input impedance. 

 

The use case is that you want to use the VDI cable to power the Variax and allow Helix control of the Variax. But you want to retain the 1/4" output to Helix guitar input to retain the tone, and to properly respond to the impedance set in your patch.

 

I think this is a perfectly valid use case, and should be supported. The fact that using a 1/4" TS cable in the JTV with the VDI cable can inadvertently load down the VDI power is unfortunate but real. Best to avoid it as suggested many times above.

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AH! There we go - I think I'm starting to get why this is a "touchy" issue! It's the digital vs analog thing! I get that. But if plugging into the Helix, with either connection, is where you are going, guess the signal is going digital one way or the other. So, plug the 1/4" into your Marshall stack for the mags only, OR plug the ethernet looking thing into your Helix. I'm a little on the analog side of that argument. Well, at least for live stuff. Recording . . . that VDI thing ROCKS with the Helix! Haven't quite gotten into the groove with the JTV89F VDI in live situations. Makes the whole guitar feel, not sure how to explain it, I guess "Mushy" might be the best description. Signal just oozes through the (ethernet looking thing) cable like molasses. Not sure I'll ever get used to that. Maybe someday I'll figure out I was doing something wrong, and find out how to make the digital side sound (and FEEL) amazing live! But, that is a topic for a different thread.

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The difference is where the A2D conversion is being done - with VDI its done in Variax, with 1/4" its done in Helix. I do think there is both a tone difference and sustain difference. To me the 1/4" sounds more natural, and sustains longer, and dies out without odd warbles. There's probably a number of reasons for this. First the A2D converters are probably different - Helix might have better converters. Second is the Helix 1/4" input has wide dynamic range and programmable input impedance, the input preamps might be better in Helix than in Variax. Finally,  the Line6 VDI cable is 25' long. That's a lot of opportunity for jitter and noise to get into the digital signal and cause errors at the Helix input. 

 

From all the posts above, its still not clear to me if/why the TS 1/4" can't be run with the VDI cable at the same time -  as long as there's no battery in the Variax. The point is there should only  be one power source at a time. @psarkissiancould you clarify.

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" I think I'm starting to get why this is a "touchy" issue! It's the digital vs analog thing! "--- close,...

it's an impedance, current draw, load thing. Running both outputs simultaneously puts a current draw

load that it was not designed to handle. Good guess though.

 

"... should only  be one power source at a time. "--- yes, very good, that too. It goes back to the load thing.

 

Also TS vs TRS. Since the mid 1970's, when us crazy circuit geeks did active guitar circuits, TRS (tip/ring/sleeve) plugs have always been used.

It became something of the de-facto standard back then. The same pin-out is used today,... tip= signal, ring= +Vdc, sleeve= the return (ground).

 

" First the A2D converters are probably different - Helix might have better converters. Second is the Helix 1/4" input has wide dynamic range and programmable input impedance, the input preamps might be better in Helix than in Variax. Finally,  the Line6 VDI cable is 25' long. That's a lot of opportunity for jitter and noise to get into the digital signal and cause errors at the Helix input. "--- good guess, not quite. Sync issues were a bit of a glitch with the X3 Live a while back (USB recording). I made a big deal about it, engineering has been more aware of sync issues since then.

 

When using the VDI, use the L6 25ft cable, that's for playing through. Don't use that short thing that comes with the guitar, that's for connecting to Line 6 Monkey for Updates, and Workbench HD for doing custom patching, uploading and downloading patches,... don't play through that.

 

Very good, nothing gets by you two. Keep it up.   :)

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I think I get it. If you use VDI to power the guitar, and TS plug in the output jack at the same time, the power terminal of that TRS jack will be grounded by the TS plug. That could easily cause at least a partial short on the VDI power supply.

 

But if you used VDI to power the guitar and TRS with nothing connected to the ring, then this would seem to eliminate the short and potential additional load.

 

Although that might actually be fine, it's a lot simpler to say don't use two cables at the same time. This would prevent situations where someone used TS cables, or used a TRS cable that happened to ground the ring on the other end. It's probably better to be cautious and avoid the potential issue.

 

That said, I still think the 1/4" output sounds better than the VDI into Helix - better tone, more sustain. I wish that weren't the case since I use VDI exclusively.

 

 

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1- Yes.

2- Yes, and load down the main board. Have seen JTV's come back with component blown on VDI and/or TRS jack on the jack plate,

components blown near the jack plate-to-main board connector, the main board shorted, and on rare occasions the ultimate trifecta,...

jack plate, main board and battery box PCBA's all go down.

3- Correct, "don't use two cables at the same time", and as Egon told Venckman, "Don't cross the streams." Most double correct, "It's probably

better to be cautious and avoid the potential issue."

4- I know what you mean, I'm VDI kind of guy too.

 

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